Stripping dyed textiles



Patented Sept. 1, 1936 UNITED STATES PATE'NT. OFFICE STRIPPING DYEDTEXTILES No Drawing. Application January 30, 1935, Serial No. 4,149. InGreat Britain February 2,

21 Claims.

Dyeings of the so-called azoic colours of the Brenthol AS type, that is,of those azo dyestufis produced by combination of a 2:3-hydroxynaphthoicarylamide on the fibre with suitable diazo compounds, are as is wellknown, generally fast, and many are extremely fast to bleachingagencies. The outstanding fastness to kier-boil'ing and chlorine of suchdyeings, is evidence of this. It often becomes necessary, nevertheless,to remove the dyestuff from the fabric because of faults in the dyeing,or for other reasons, and, although this removal, or discharge, iscomparatively easily carried out locally, as in discharge printingprocesses, it is carried out only with difficulty, and at a prohibitivecost (due to the necessity of using excessive amounts of strippingagents), when a solid shade is to be entirely removed.

In United States Patent No. 2,003,928 there is described an inventionwhich has for its object the provision of a technically advantageous,economical process of stripping particularly adapted to the entireremoval of solid shades produced by azoic colours as above defined. Thisobject is accomplished according to that invention by treating textilematerial dyed with azoic colours in a chemically reducing liquor (whichmay be acid, alkaline or neutral) containing an amine or amine salt,preferably a quarternary ammonium salt, one radical in which comprises astraight or branched carbon chain of not less than 10 carbon atoms.

The liquor may be either weakly alkaline, neutral or weakly acid, but ispreferably acid when the amine is not a quaternary ammonium salt.Further while azoic dyeings as above defined on wool or silk or otheranimal fibre can be stripped satisfactorily in an alkaline bath, acertain risk is incurred owing to the possibility of injury to the fibreon account of the alkali present, it is therefore preferable to treatsuch fibres in a faintly acid bath. If desired vegetable fibre can betreated in the same manner. The acidity may be produced by means ofmineral or organic acid. The fibre is stripped white or slightly tinged.In the latter case, for vegetable fibre, a supplementary chlorine orchemick treatment may be applied further to improve the ground. In thecase 50 of animal fibre a supplementary peroxide treatment is sometimesbeneficial.

Suitable amines or amine salts are for example ,B diethylaminoethyloleylamide or its acetate or hydrochloride, heptadecylamine or its hydrochlo-55 ride, (Hofimann, Berichte, 1882, 15,774) and suitable quaternaryammonium salts, are for example octadecylpyridinium bromide,cetylpyridin- 'ium bromide, (cf. United States Appln. No.

611,236), cetylpyridinium chloride (cf. British Patent No. 392,763),octadecyltrimethylammonium (from octadecyl iodide and trimethylamine),cetyltrimethylammonium bromide, cetyltriethylammonium bromide,cetyltrimethylammonium 10 di d e, p-stearoamidophenyltrimethylamm'oniumsulphate, p-stearoamidoethyh diethylamine methosulphate (cf. BritishPatent No. 294,582), or fi-hydroxyethyl-N-octadecyl morpholinium bromide(prepared by heating together equimqlecular proportions ofp-hydroxyethylmorpholine and octadecyl bromide at 0.).

According to the present invention which is an improvement in ormodification of that described in the aforesaid specification, a smallproportion of anthraquinone or hydroxy, amino, 20 halogen or alkylsubstituted anthraquinone is added in the stripping process alreadymentioned.

In carrying the invention into practical efiect there is applied to thedyed material a hot dilute aqueous solution of a reducing agent, forexample sodium hydrosulphite, containing a small proportion of thequaternary ammonium salt and the anthraquinone or anthraquinonederivative.

The textile material is then found to be colourless, or at most to havebut a light tinge. It may be made white or-but slightly tinged by afurther treatment, if necessary, in a weak solution of sodiumhypochlorite or otherbleaching liquor.

The present process possesses various advantages over the processdescribed in United States Patent No. 2,003,928. The process generallyspeaking can be carried out at a lower temperature than when theaddition of anthraquinone to the bath is omitted, and the time necessaryfor effective stripping action to be effective is frequently reduced.Further it facilitates the strip-' ping of certain azoic colours whichby known processes are diflicult to remove from'the fibre. Finally it isof particular interest in the stripping of azoic colours from naturalsilk, dyeings on this fibre being more resistant to stripping agentsthan are the corresponding dyeings on cotton.

The invention also includes new preparations for stripping textilefibres, which comprise an 50 amine or amine salt as already describedand anthraquinone or an anthraquinone derivative, with, if desired, asoluble hydrosulphite.

The following examples in which parts are by weight illustrate but donot limit the invention.

Example 1 Cotton yarn dyed a. full shade by means of Brenthol AT(diacetoacetictoluidide) coupled with diazotized 4 chloro 2 aminotoluenehydrochlo ride, is treated for 30 minutes at 85-90" C. in 40 times itsweight of anaqueous solution prepared by adding 1.25 parts of causticsoda, 1.25 parts sodium hydrosulphite (conc. powder) and 0.5 part oftrimethylcetylammonium bromide to 1000 parts of water, in which isdispersed 0.5 part of finely powdered anthraquinone.

This treatment reduces the colour of the yarn to a pale yellow shadewhich may be stripped to a white by treatinent for 30 minutes in sodiumhypochlorite solution (34 Tw.).

Example 2 Cotton yarn dyed a full shade by means of Brenthol AS (anilideof 2:3-hydroxynaphthoic acid) coupled with-diazotized-chloro-2-aminotoluene is heated for 30 minutes at 50 C. in 40 times itsweight of an aqueous solution prepared by adding 2.5 parts of causticsoda, 4 parts of sodium hydrosulphite (concentrated powder) and 0.5 partof trimethylcetylammonium bromide to 1000 parts of water in which isdispersed 0.5 part of finely powdered anthraquinone. The colourisdischarged. A treatment in cold solution of sodium hypochlorite /2 Tw.)clears the residual stains and a white yarn is produced.

A corresponding treatment omitting anthraquinone strips the colour to apale red shade whilst a treatment omitting both anthraquinone andtrimethylcetylammonium bromide leaves the colour almost unchanged.

Example 3 Cotton yarn dyed a full shade by means of Brenthol BT(2-hydroxycarboazol-3-carboxylic acid p-chloroanilide) coupled withdiazotized S-nitro-o-anisidme is treated for 16-hours at 20 C. in 40times its weight of an aqueous solution having the same composition asthat described in Example 2. The yarn is then rinsed and transferred toa cold solution of sodium hypochlorite Tw.) for hour. It is then scouredby immersion in dilute hydrochloric acid for a few minutes, rinsed anddried. The colour of the yarn is a pale brown tint.

By treating the dyed yarn in a corresponding manner, omitting theaddition of anthraquinone, the yarn is stripped to alight brown shadewhilst a treatment omitting both anthraquinone andtrimethylcetylammonium bromide exerts practically no stripping action.

Example 4 A treatment of yarn dyed a full shade by means of Brenthol AT(diacetoacetictoluidide) coupled with diazotized 5-nitro-o-anisidine bythe same method and using a solution having the same composition asemployed in Example 3, strips the colour to a pale orange. I

A corresponding treatment omitting anthraquinone reduces the colour to amedium orange yellow shade, whilst a treatment omitting bothanthraquinone and trimethylcetylammonium bromide has practically nostripping efiect.

Example 5 employed in Example 3 strips the colour to pale greyish tint.

A corresponding treatment omitting anthraquinone reduces the shade to apale dull shade whilst a treatment omitting anthraquinone andtrimethylammonium bromide produces scarcely any change in the originalheavy navy blue shade.

Example 6 Pure silk yarn dyed a full shade by means of Brenthol BAcoupled with diazotized fast red KB base is heated at the boil in 40times its weight Example 7 Example 8 Pure silk yarn dyed a full shade bymeans of Brenthol BA coupled with diazotized 4-nitro-oanisidine isheated at the boil in 40 times its weight of a solution prepared bydissolving 2 parts of 30% acetic acid, 4 parts Formo'sol and 0.5 parttrimethyldodecylammonium'bromide in 1000 parts of water and adding 0.5part of finely divided anthraquinone. The colour is discharged afterheating for 40 minutes.

A treatment for the same time using a similar solution except that theanthraquinone is omitted. only strips the yarn to a light pink shade.

I claim:

l. A stripping bath containing trimetlrvlcetylammonium bromide andfinely powdered anthraquinone. I

2. A composition of matter useful in stripping the colorfrom materialsdyed with azo dyes, ,com-

prising a dilute aqueous solution of sodium hydrosulfite, one of a groupof compounds consisting of an amine having a straighter branch chain ofat least ten carbon atoms and an amine salt having a straight or branchchain of at least ten carbon atoms, and one of a group of compoundsconsisting of anthraquinone, hydroanthraquinone, aminoanthraquinone,halogenoanthraquinone, and alkylanthroquinone.

-3. A composition of matter useful in stripping the color from materialsdyed withvazo dyes, comprising a dilute aqueous solution of a reducingagent of the hydrosulfite type, one of a group of compounds consistingof an amine having a straight or branch chain of at least ten carbonatoms and an amine salt having a straight or branch chain of at leastten carbon atoms. and

anthraquinone. H a of matter useful in stripping alkylanthraquinone, theanthraquinone ingredione of a group of compounds consisting ofanthraquinone, hydroanthraquinone, aminoanthraquinone,halogenoanthraquinone, and alkylanthraquinone.

the color from materials dyed with azo dyes comprising, a solution of areducing agent, one of a group of compounds consisting of an aminehaving a straight or branch chain of at least ten carbon atoms and anamine salt having a straight or branch chain of at least ten carbonatoms, and one of a group of compounds consisting of anthraquinone,hydroanthraquinone, aminoanthraquinone, halogenoanthraquinone, andalkyl- 5. A composition the color from materials dyed with azo dyes,

comprising water, one of a group of compounds consisting of an aminehaving a straight or branch chain of at least ten carbon atoms and anamine salt having a straight or branch chain of at least ten carbonatoms, and one of a group of compounds consisting of anthraquinone,hydroanthraquinone, aminoanthraquinone, halogenoanthraquinone, andalkylanthraquinone.

6. A composition of matter useful in stripping the color from materialsdyed with azo dyes comprising water, anamine having a straight or branchchain of at least carbon atoms and one of a group of compoundsconsisting of anthraquinone, hydroanthraquinone, aminoanthraquinone,halo'genoanthraquinone, and alkylanthraquinone.

'7. A composition of matter useful in stripping the color from materialsdyed with azo dyes, comprisingwater, an amine salt having a straight orbranch chain of at least ten carbon atoms, and one of a group ofcompounds consisting of anthraquinone, hydroanthraquinone,aminoanthraquinone, halogenoanthraquinone, and alkylanthraquinone.

8. A composition of matter useful in stripping the color from materialsdyed with azo dyes, comprising water, a tertiary amine having a straightor branch. chain of at least ten carbon atoms and one of a group ofcompounds consisting of anthraquinone, hydroanthraquinone,aminoanthraquinone, halogenoanthraquinone, and alkylanthraquinone.

9. A composition of matter useful in stripping the color from materialsdyed with azo dyes, comprising water, a tertiary amine having a straightor branch chain of at least ten carbon atoms and one-of a group ofcompounds consisting of anthraquinone, hydroanthraquinone,aminoanthraquinone, halogenoanthraquinone, and

cut being present in a weight about .05% of that of the bath.

10. A composition of matter useful in stripping the color from materialsdyed with azo dyes, comprising tri'methylcetylammonium bromide and oneof a group of compounds consisting of anthraquinone, hydroanthraquinone,aminoanthraquinone, halogenoanthraquinone, and alkylanthraquinone.

11. A composition of matter useful in stripping the color from materialsdyed with azo dyes, comprising trimethylcetylammonium bromide andanthraquinone.

. 12. The method of stripping materials dye with azo dyes whichcomprises acting on the materials with a bath containing the ingredientsof claim 2.

13. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 3.

14. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 4.

15. The process .of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 5.

16. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materialswith a bath containing theingredients of claim 6.

1'7. The process of stripping materials dyed with azo dyes whichcomprises acting on'the dyed materials with a bath containing theingredients of claim 7.

18. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 8.

19. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 9.

20. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 10.

21. The process of stripping materials dyed with azo dyes whichcomprises acting on the dyed materials with a bath containing theingredients of claim 11.

CHARLES DUNBAR'.

